title: Casein kinase II-mediated phosphorylation of general repressor Maf1 triggers RNA polymerase III activation.
abstract: Maf1 protein is a global negative regulator of RNA polymerase (Pol) III transcription conserved from yeast to man. We report that phosphorylation of Maf1 by casein kinase II (CK2), a highly evolutionarily conserved eukaryotic kinase, is required for efficient Pol III transcription. Both recombinant human and yeast CK2 were able to phosphorylate purified human or yeast Maf1, indicating that Maf1 can be a direct substrate of CK2. Upon transfer of Saccharomyces cerevisiae from repressive to favorable growth conditions, CK2 activity is required for the release of Maf1 from Pol III bound to a tRNA gene and for subsequent activation of tRNA transcription. In a yeast strain lacking Maf1, CK2 inhibition showed no effect on tRNA synthesis, confirming that CK2 activates Pol III via Maf1. Additionally, CK2 was found to associate with tRNA genes, and this association is enhanced in absence of Maf1, especially under repressive conditions. These results corroborate the previously reported TFIIIB-CK2 interaction and indicate an important role of CK2-mediated Maf1 phosphorylation in triggering Pol III activation.
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02 106 Warsaw, Poland.
authors.forename: Damian
authors.initials: D
authors.lastname: Graczyk
authors.forename: Janusz
authors.initials: J
authors.lastname: Debski
authors.forename: Grazyna
authors.initials: G
authors.lastname: Muszyńska
authors.forename: Maria
authors.initials: M
authors.lastname: Bretner
authors.forename: Olivier
authors.initials: O
authors.lastname: Lefebvre
authors.forename: Magdalena
authors.initials: M
authors.lastname: Boguta
mesh_terms: D047390:Casein Kinase II / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D010766:Phosphorylation; D012320:RNA Polymerase III / Q000235:genetics / Q000378:metabolism*; D012343:RNA, Transfer / Q000096:biosynthesis* / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D035361:Transcription Factor TFIIIB / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: C104954:MAF1 protein, S cerevisiae; C520535:MAF1 protein, human; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D035361:Transcription Factor TFIIIB; D014157:Transcription Factors; D012343:RNA, Transfer; D047390:Casein Kinase II; D012320:RNA Polymerase III